Modern wireless communication systems may operate according to Institute of Electrical and Electronics Engineers (IEEE) standards such as the 802.11 standards for Wireless Local Area Networks (WLANs) and the 802.16 standards for Wireless Metropolitan Area Networks (WMANs). Worldwide Interoperability for Microwave Access (WiMAX) is a wireless broadband technology based on the IEEE 802.16 standard of which IEEE 802.16-2004 and the 802.16e amendment are Physical (PHY) layer specifications. IEEE 802.16-2004 supports several multiple-antenna techniques including Alamouti Space-Time Coding (STC), Multiple-Input Multiple-Output (MIMO) antenna systems, and Adaptive Antenna Systems (AAS).
Frequency reuse in cell-based WMANs and WLANs leads to the appearance of cochannel interference. Cochannel interference is considered as a main limiting factor that restricts spectral efficiency and capacity of high-throughput wireless systems. Future wireless communication systems are expected to support many MIMO transmission techniques such as STC and spatial multiplexing. It is evident that variety of adopted transmission techniques will cause different types of complex MIMO interferences such as MIMO space-time coded cochannel interference from a neighboring station which simultaneously transmits signal combination from several antennas.
Traditional cochannel interference cancellation (CIC) techniques are based on using difference in spatial correlations of useful and interference signals only. Such “space-only” CIC techniques do not take into account signal time correlation properties. Therefore, to suppress complex MIMO interference, it is necessary for the receiver side to have additional antenna elements equal to the number of transmit antennas at the interference source. To cancel Alamouti space-time interference, for example, it is necessary for a system to employ two additional receive antennas.